1. Field of the Invention
The description relates to a process for the recovery of a useful, polymerizable fraction, consisting of styrene, methylstyrenes, vinyltoluenes, indene, methylindenes and fractions whose boiling points are between styrene and methylindenes, from the crack gases of a steam cracker.
The above useful fraction is a starting material for various adhesive resins.
2. Description of the Related Art
Processes for the recovery of similar useful fractions are known and are described in the patent literature. For example, Japanese Patent 87-190136 describes a process in which a polymerizable fraction of C.sub.9 -C.sub.10 -cuts is recovered from residue oil by means of distillation. U.S. Pat. No. 4,371,428 describes a process for separating vinyl toluene from other alkenyl aromatics by means of extraction distillation. For the recovery of indene, U.S. Pat. No. 4,827,078 describes a process which relates to the recovery from a petrochemical mixture by means of adsorption using zeolites.
The processes described have various disadvantages, for example the fact that the desired useful fraction is first recovered from the residue oil and is thus subjected to high thermal stresses. Furthermore, the processes described are energy-consumptive.